The announcement is expected around noon Eastern Time, a National Postal Mail Handlers Union representative said.? A self-imposed moratorium on potential closures within its mail processing network ended Tuesday.

In December, the Postal Service announced plans to close and consolidate hundreds of its mail processing and distribution centers.

In April, the agency released a list of centers that could remain open. It included the sorting facilities in White River Junction and Plattsburgh.

The Postal Service notified its employees of the changes at its facilities across the country Wednesday night.

According to Postal Service documents provided by the APWU, the agency will begin consolidating and closing plants this summer. No plants will close between September and December due to the election and holiday season. Phase One of planned closures will continue in January 2013 with a second phase in 2014.

The list of plants to close was not released as of Wednesday evening -- though an announcement is expected Thursday.

Several dozen closings are expected, a NPMHU representative said.? A new delivery service standard will also be put in place next year, a APWU representative said.

“Prior to public release of any additional information, our top priority, as is standard operating procedure, is to ensure our employees are notified first,” said Tom Rizzo, a Postal Service spokesman. “America needs a financially-stable Postal Service to adapt to a changing marketplace and evolving mailing needs. The steps we are taking now will put the Postal Service on a strong financial footing for decades to come.”

The U.S. Senate passed a bill in April that would allow the agency to recoup billions of dollars in overpayments. It also would allow for the Postal Service to pay for early retirements and fund new methods of service.

The bill has stalled in the House of Representatives, with a vote not possible until next month.

The Postal Service had originally planned to close 3,700 rural post offices, as well as about 250 processing centers. It later revised the plant closures to about 100, though a final list has not been released.

Last week, the agency said it would keep the 3,700 rural offices open, but shorten hours at 13,000 offices nationwide.

On Monday, the Postal Service announced plans to hold off closing 600 urban and suburban offices.

According to the Postal Service talks given to employees, the agency lost $3.2 billion this quarter, with year-to-date losses totaling $6.5 billion.